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The onset and association of CMEs with sigmoidal active regions
Author(s) -
Glover Alexi,
Ranns Neale D. R.,
Harra Louise K.,
Culhane J. Leonard
Publication year - 2000
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2000gl000018
Subject(s) - sigmoid function , inverse , association (psychology) , term (time) , astrophysics , physics , mathematics , artificial intelligence , computer science , psychology , astronomy , geometry , artificial neural network , psychotherapist
Previous studies of active regions characterised by Soft X‐ray S or inverse‐S morphology [ Canfield et al., 1999], have found these regions to possess a higher probability of eruption. In such cases, CME launch has been inferred using X‐ray proxies to indicate eruption. Active regions observed during 1997, previously categorised as both sigmoidal and eruptive [ Canfield, 1999], have been selected for further study, incorporating SoHO‐LASCO, SoHO‐EIT and ground based H‐alpha data. Our results allow re‐classification into three main categories; sigmoidal, non‐sigmoidal and active regions appearing sigmoidal due to the projection of many loops. Although the reduced dataset size prevents a statistical measure of significance, we note that regions comprising a single S (or inverse‐S) shaped structure are more frequently associated with a CME than those classed as non‐sigmoidal. This motivates the study of a larger dataset and highlights the need for a quantitative observational definition of the term “sigmoid”.